GMAT Strategy

Hi everyone, I thought I'd share on here just to see if anyone's been in the same boat. I've been studying for this thing every day since mid-February, taking prep courses and tutoring, and taking practice CATs every week bar one week. I've been on a rollercoaster ride in terms of scores, I started with a 500 on a diagnostic, then gradually went up to a 580, then dipped to a 520 again, then went back up to 580, then, in a dramatic increase, got a 650 on a CAT last weekend. I was really excited because I take the real thing on the 19th (now a week away), and thought I could reach my target of around 700.

Today, I took the old GMATPrep software practice CAT 1 (after taking the new one with integrated reasoning and getting a 580 a month ago), and got a 530. I feel like garbage. Is there any explanation for this that you've heard of? Was my score last week artificially inflated last week? I really don't want to push the test back to after June 5th, and my schedule is really inflexible so I don't really have any options in terms of when I can take it other than next Saturday. I have 2 more sessions with my tutor. Should I just not take the thing and save myself the disappointment?

Anyway I apologize for the Debby Downer of a post on such a beautiful Saturday (at least here in the NYC area), and I appreciate any feedback.

PS: Let's Go Rangers tonight vs the Capitals.